Photorefractive hyper-structured molecular glasses constructed by calix[4]resorcinarene core and carbazole-based methine nonlinear optical chromophore

•Seven CRA-based photorefractive (PR) hyper-structured molecular glasses (HSMGs) were synthesized by esterification.•The degrees of introduction of bulky NLO chromophores to the CRA core were higher than 70%.•The Γ values of HSMGs composites are about two times of the corresponding small molecular functional compounds composite.•The Γ value of CRA-CSN/ECz/PCBM (69:30:1, wt.%) composite was 78.2 cm−1 at the external electric field of 12.5 V mm−1.

Seven C-methylcalix[4]resorcinarene (CRA)-based photorefractive (PR) hyper-structured molecular glasses (HSMGs) containing carbazole-based methine nonlinear optical (NLO) chromophores were designed and synthesized via esterification between carboxyl-containing asymmetric CRA core molecule and hydroxyl-containing functional compounds. When the feed ratio of hydroxyl-containing NLO functional compounds to carboxyl groups of CRA-COOH was kept at 1.5/1 by mole, the degree of introduction of NLO chromophore to the CRA core was above 70%. All the HSMGs show low glass transition temperatures (Tg), and good solubility in common low boiling point solvents such as THF, CHCl3, etc. Powder XRD and UV–vis absorption in films of HSMGs indicate that the aggregation, packing and crystallization of the NLO chromophores in these HSMGs had been effectively reduced. Doping with N-ethyl-carbazole (ECz) as a plasticizer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a photosensitizer, all the HSMGs composites showed good PR effects. All the coupling gain coefficients (Γ) of HSMGs-based composites are about twice to the corresponding small molecular NLO chromophores-based composites, thanks to the decreased NLO chromophores antiparallel packing caused by the asymmetric CRA core. Among them, CRA-CSN/ECz/PCBM (69:30:1, wt%) composite exhibited the best performance with the Γ value of 78.2 cm−1 at the external electric field of 12.5 V μm−1, which is one of the best performance in molecular glasses under the same test conditions. Coupled with their convenient synthesis, this work will provide a new simple design strategy for organic PR materials.

Graphical abstractC-methylcalix[4]resorcinarene(CRA)-based photorefractive (PR) hyper-structured molecular glasses (HSMGs) containing carbazole-based methine nonlinear optical (NLO) chromophores were designed and synthesized by the esterification between carboxyl-containing asymmetric CRA core molecule and hydroxyl-containing NLO functional compounds. All the two beam coupling gain coefficients of HSMGs composites are about two times of the corresponding NLO functional compounds composite due to the decrease of NLO chromophores antiparallel packing caused by the asymmetric CRA core.Figure optionsDownload full-size imageDownload high-quality image (186 K)Download as PowerPoint slide